The present invention relates generally to a cellular communication apparatus, and, more particularly, to a radio telephone interface apparatus permitting speed-dialing of sequences of digits forming telephone numbers.
A communication system is comprised, at a minimum, of a transmitter and a receiver interconnected by a communication channel. A radio communication system comprises one type of communication system wherein the communication channel interconnecting the transmitter and the receiver is formed of a radio frequency channel. No fixed connection is required between the transmitter and receiver of a radio communication system. Therefore, a radio communication system is advantageously utilized when a fixed connection between the transmitter and the receiver would be inconvenient or impractical.
A cellular, communication system is one type of radio communication system. In a cellular, communication system, numerous fixed-site transceivers, referred to as "base stations", are installed at spaced-apart locations throughout a geographical area. Each of the base stations contains circuitry to receive modulated signals transmitted thereto, and to transmit modulated signals therefrom. A radio telephone transmits the modulated signals to a base station, and a base station transmits the modulated signals to the radio telephone. The modulated signals are transmitted upon selected frequency channels allocated for such cellular communications.
A plurality of radio telephones may be operated simultaneously when the modulated signals transmitted by the different radio telephones are transmitted upon dissimilar frequency channels. (The modulated signals transmitted by base stations to the radio telephone are similarly transmitted upon dissimilar frequency channels.) As the power levels of the modulated signals generated by both the radio telephones and the base stations are relatively low, the same frequency channel may be reused throughout a geographical area to transmit the modulated signals between a radio telephone and a base station. In such manner, a cellular, communication system efficiently utilizes the frequency channels of the frequency band allocated for such use.
Technological improvements have decreased the cost associated with cellular communications. As a result, ever-increasing numbers of users make use of a cellular, communication system to communicate thereupon. Of particular popularity is the use of a radio telephone to communicate upon a cellular, communication system when the user is traveling in an automotive vehicle. Radio telephones constructed for installation within an automotive vehicle are conventionally referred to as mobile phones. As no fixed connection is required between the radio telephone and a base station, communication is permitted therebetween as long as the vehicle in which the radio telephone is positioned is within the geographical area encompassed by the cellular, communication system.
The steps required to be taken to effectuate a communication link between a radiotelephone and a base station, such as a mobile phone are quite similar to the steps required to be taken to effectuate communication when utilizing a telephone of a conventional, wire line system. Namely, a hook switch is released (conventionally occurring when a telephonic handset is removed from a base portion thereof), and a sequence of digits which form the telephone number are dialed or otherwise entered. The telephone number is associated with a particular telephone situated at a remote location.
Quite frequently, when the radio telephone is positioned in an automotive vehicle, the user of the phone is also the operator of the vehicle. When operating the vehicle, primary attention must be directed to that task, and only minimal attention may be allocated to taking the steps required to effectuate communication upon the cellular, communication system. Although the required step of dialing of a telephone number is not, of itself, a complex task, visual inspection of the telephone keypad is typically required of the user to ensure correct dialing of the telephone number. This visual inspection required to dial the telephone number detracts from the attention which must be directed to operating the automotive vehicle.
To minimize the usual inspection required to dial the telephone number, therefore, mobile phone constructions frequently include features to simplify the task of effectuating a communication link with a base station. For instance, the speaker and microphone, conventionally mounted upon a telephonic handset, are, in some mobile phone constructions, also fixedly mounted within the vehicular compartment of the automotive vehicle. Rather than holding a telephonic handset to position the speaker and microphone proximate to the user, the user may speak towards the microphone mounted in a fixed position in the vehicular compartment and listen to signals generated by the speaker similarly mounted in fixed position therein. Such a feature is frequently referred to as a "hands-free" feature permitting "hands-free" operation of the mobile phone.
Additionally, existing mobile phone constructions frequently include features to reduce the number of steps necessary to dial a telephone number. Analogous to conventional, wire line telephonic constructions permitting "speed-dialing", mobile phone constructions include features permitting such dialing of a telephone number. Conventionally, a switch is associated with a single telephone number, and when the switch is actuated, the telephone number associated therewith is dialed. When appropriately positioned in the vehicular compartment of the automotive vehicle, the operator of the automotive vehicle, upon memorizing the location of the switch, can dial the telephone number associated therewith by actuation of the switch. However, as the switch is associated with a single telephone number (i.e., there is a one-to-one correspondence between the switch and the telephone number), an increase in the number of telephone numbers which may be "speed-dialed" requires a corresponding increase in the number of switches. The location of each switch must be memorized to avoid the requirement of a user to inspect visually the location of the switch prior to actuation thereof. With each additional switch, the likelihood that the user, either as an impulse or as of necessity, must visually inspect the location of the switch prior to actuation thereof increases, as the user must both memorize the locations of the switches and the telephone numbers associated therewith to actuate a switch without first making a visual location thereof. As the attention of the operator of an automotive vehicle must be directed primarily to the operation of a vehicle, such a need or impulse to locate visually a switch prior to actuation thereof detracts from the operator's attention which should otherwise be directed towards operation of the automotive vehicle.
What is needed, therefore, is an improved interface apparatus for a radio telephone permitting speed-dialing of a desired number of pre-stored telephone numbers.